1. Field of the Invention
The present invention relates to a time code discrimination apparatus that discriminates a time code and a wave clock that receives a standard radio wave to discriminate a time code.
2. Description of Related Art
In recent years, wave clocks that receive a time code and automatically correct time of an internal clock have been used. The time code is transmitted by performing the amplitude modulation (AM) on a carrier wave of 40 kHz or 60 kHz. If radio wave conditions are bad, a signal waveform of the received, time code may be collapsed, and it may be difficult to discriminate the time code.
As techniques for receiving and discriminating the time code, a technique for receiving only partial data of a time code and correcting time at a high speed (for example, refer to U.S. Pat. No. 7,411,870) or a technique for adjusting a threshold level to discriminate a time code signal and enabling accurate reproduction, of a time code even though radio wave conditions are poor (for example, refer to Japanese Patent Application Laid-Open No. 2007-139705 and U.S. Pat. No. 7,428,190) have been proposed.
Although the conventional technique for receiving and discriminating a time code can improve the sensitivity slightly, the conventional technique cannot improve the sensitivity to such a degree that accurate discrimination of the time code can be achieved under the condition that a signal is greatly attenuated and a noise ratio is increased, such as in a building.
Further, if the normal discrimination of the rime code is not performed, reception of the time code is performed several times. As a result, power consumption is increased.